1. Field of the Invention
The present invention relates to a vibration wave motor which displaces a movable member such as a rotor by a vibration wave generated by an electro-mechanical energy transducer such as an electrostrictive element or piezoelectric element.
2. Related Background Art
A vibration wave motor which displaces a movable member by applying a travelling wave to the movable member frictionally engages with a vibration member on which an electostrictive element is arranged, the travelling wave being generated on the vibration member by applying a drive signal to the electrostrictive element, has been known by, for example, U.S. Pat. No. 4,484,099 (issued on Nov. 20, 1984) and U.S. application Ser. No. 561,550 (filed on Dec. 14, 1983).
In such a vibration wave motor, the movable member is press-contacted to the vibration member by a biasing member and the movable member is driven by a travelling vibration wave generated in the vibration member. In such a prior art motor, if a flexure of the biasing means varies for some reason, the pressure between the vibration member and the movable member changes and a characteristic of the motor changes.